Machine for forming metal stampings having an edge portion folded over on itself

ABSTRACT

A machine for forming metal stampings comprising an upper die holder on which an upper die half and an upper clamping yoke are mounted; a lower die holder on which a lower die half and a lower clamping yoke are mounted; handling means suitable to achieve the bringing together and moving apart of the upper die holder and the lower die holder; and an edge cutting/bending unit suitable to carry out both the cutting and bending of the edge and arranged between the two die halves and the two clamping yokes. The edge cutting/bending unit comprises a cutting blade suitable to cut the edge of a sheet to be formed; an outer bending blade arranged below said cutting blade and which forms a pushing step with it, facing in use towards said upper die half and said lower die half, and an inner bending blade arranged to slide along said outer bending blade.

TECHNICAL FIELD

The present invention relates to a machine for forming metal stampings having an edge portion folded over on itself.

BACKGROUND ART

The requirement to have a metal stamping with an edge folded over on itself is common to many products, for both aesthetic and safety reasons.

As is well known to a person skilled in the art, the production of metal stampings having an edge folded over onto itself currently requires a sequence of operations each of which is performed by different machinery. In other words, the edge portion of the metal stamping is folded over on itself through several bending operations, each of which is carried out by different machinery.

As may be immediately seen, such a procedure for achieving the folding of the edge portion results in both a significant encumbrance and extremely lengthy production times. Both of these aspects necessarily constitute disadvantages in terms of productivity.

There is therefore a need to have a single machine, the technical characteristics of which make it possible to achieve the forming of a metal stamping, including achieving the folding of the edge portion, in a single solution.

DISCLOSURE OF INVENTION

The subject of the present invention is a machine for forming a metal stamping, the essential characteristics of which are set forth in claim 1, and whose preferred and/or auxiliary characteristics are indicated in claims 2-5.

BRIEF DESCRIPTION OF THE DRAWINGS

Below is a non-limiting example of an embodiment purely by way of illustration with reference to the figures of the accompanying drawings, wherein:

FIGS. 1 to 7 are cross-sections of the machine which is the subject of the present invention, in respective forming steps; and

FIG. 8 in particular is a cross-section along the line VIII-VIII of FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

In FIGS. 1-7 a machine for forming metal stampings according to the present invention is indicated as a whole with 1. The machine 1 comprises a movable upper die holder 2 on which an upper die half 3 is mounted, and a fixed lower die holder 4 on which a lower die half 5 is mounted. The upper die holder 2 is movable with respect to the lower die holder 4, to operate two guide columns 6, each of which has a first end attached to the upper die holder 2 and a second end attached to the lower die holder 4. The upper die half 3 and the lower die half 5 comprise respective, mutually complementary, forming surfaces 3 a and 5 a, the coupling of which defines the shape of the metal stamping S.

The machine 1 comprises an upper clamping yoke 7 mounted on the upper die holder 2 and a lower clamping yoke 8 mounted on the lower die holder 4. The upper clamping yoke 7 is arranged so as to surround the upper die half 3 and moves integrally with it. Similarly, lower clamping yoke 8 is arranged so as to surround the lower die half 5. The upper clamping yoke 7 and lower clamping yoke 8 mutually cooperate in the clamping operation of the edge portion of a sheet that will constitute the stamping.

The machine 1 comprises an edge cutting/bending unit 9 arranged so as to surround the upper die half 3 and the lower die half 5 and positioned in a space between the two die halves and the two clamping yokes 7 and 8.

The edge cutting/bending unit 9 comprises a cutting blade 10 which is specifically arranged to surround the upper die half and is positioned between it and the upper clamping yoke 7. The cutting blade 10 is attached to a handling plate 11, which is in turn attached to the upper die holder 2. In this respect, the upper die holder 2 comprises a plurality of damper pistons 12 which make possible the movement of the handling plate 11 and therefore of the cutting blade 10 even when the upper die half 3 has reached the end of its travel onto the lower die half 5.

The edge cutting/bending unit 9 comprises an outer bending blade 13 which is arranged to surround the lower die half 5 and is positioned between it and the lower clamping yoke 8. The outer bending blade 13 is attached to a handling plate 14 on which the plurality of pistons 15 act. In particular, as clearly shown in the respective enlargements of FIGS. 2-6, the outer bending blade 13 is arranged directly below the cutting blade 10 in such a way that the vertical movement of the cutting blade must be accompanied by an opposite movement of the outer bending blade 13 and vice versa.

In particular, the outer bending blade 13, having a thickness greater than that of the cutting blade 10 forms with the latter a step G facing toward the lower die half 5. As described below, the presence of this step G serves a function in a first and a second bending operation of the edge portion.

The edge cutting/bending unit 9 comprises an inner bending blade 16 which is arranged to surround the lower die half 5 and is positioned between it and the outer bending blade 13. The inner bending blade 16 is attached to a handling plate 17 on which a piston 18 acts.

As shown in the enlargements of FIGS. 2-6, the inner bending blade 16 has an oblique upper surface 19. As described below, the inner bending blade 16 has the function of completing the operation of the edge portion bending on itself.

In particular, as shown in FIG. 8, the outer bending blade 13 and the inner bending blade 16 have two respective toothed sliding surfaces 13 a and 16 a which are mutually interlocked and arranged to slide against each another. The teeth of the toothed sliding surfaces 13 a and 16 a have a trapezoidal shape.

The following describes the operation of the machine which is the subject of the present invention with reference to the sequence of operations illustrated in FIGS. 1-7.

As shown in FIG. 1, when the machine is in its open configuration, with the upper die holder 2 spaced apart from the lower die holder 4, a metal sheet L is inserted into the machine 1 resting on the lower clamping yoke 8.

As shown in FIG. 2, the machine is brought into its closed position by the operation of the two guide columns 6. In the closed position the upper clamping yoke 7 is arranged in abutment on the lower clamping yoke 8 to achieve the clamping of the sheet L and, simultaneously, the forming surface 3 a of the upper die half 3 is forced onto the forming surface 5 a of the lower die half 5 thus moulding the sheet L to form the stamping S.

As shown in FIG. 3, once the forming of the sheet L has taken place by means of the coupling of the two forming surfaces 3 a and 5 a, the shearing of the edge takes place by means of the downward movement of the cutting blade 10. In particular, the downward movement of the cutting blade always takes place by the action of the guide columns 6 and this is made possible because the damper pistons 12 ensure the downward movement of the handling plate 11 and therefore of the cutting blade 10, despite the upper die half 3 having reached the end of its travel onto the lower die half 5.

As is apparent from the enlargement of FIG. 3, while the cutting blade 10 and the outer bending blade 13 move downwards, the inner bending blade remains stationary and this causes the portion of the edge cut by the cutting blade 10 to be folded, arranging itself in the space formed by the step G between the cutting blade 10 and the inner bending blade 16.

At this point, the first bending operation being made, as clearly shown in the enlargement of FIG. 4, the inner bending blade 16 moves downwards in order to leave the space necessary to achieve a second bending operation clearly shown in the enlargement of FIG. 5. The second bending operation is carried out by the upward movement of the outer bending blade 13 and therefore of the cutting blade 10, while the inner bending blade 16 remains stationary. The upward movement of the outer bending blade 13 carries out the second bending operation because the step G engages with the already folded edge portion, sliding and thus forcing it into a further bending inside the space left free by the downward movement of the inner bending blade.

As clearly illustrated in the enlargement of FIG. 6, the third and last bending operation takes place by means of the upward movement of the inner bending blade which, thus, compresses the edge portion against a peripheral portion of the forming surface 3 a of the die half 3.

At this point, the stamping is completed with the edge portion folded and the machine 1 is returned to its open configuration (FIG. 7) and the stamping can be removed.

From the above description, it is clear how the machine which is the subject of the present invention makes it possible to carry out the forming of a stamping ensuring, at the same time, the bending of an edge portion.

Being able to have a single forming machine for the creation of the stamping in its entirety (including the bending of the edge portion) certainly provides a great advantage in terms of productivity. In fact, the machine of the present invention makes possible a significant reduction in space and an equally significant reduction in throughput times. 

1. A machine for forming (1) metal stampings comprising an upper die holder (2) on which an upper die half (3) and an upper clamping yoke (7) are mounted; a lower die holder (4) on which a lower die half (5) and a lower clamping yoke (8) are mounted; handling means (6) suitable to achieve the bringing together and moving apart of the upper die holder (2) and the lower die holder (4); and an edge cutting/bending unit (9) suitable to carry out both the cutting and bending of the edge and arranged between the two die halves (3, 5) and the two clamping yokes (7, 8); said edge cutting/bending unit (9) comprising a cutting blade (10) suitable to cut the edge of a sheet to be formed; said forming machine (1) being characterised in that said edge cutting/bending unit (9) comprises: an outer bending blade (13) arranged below said cutting blade (10) and which forms a pushing step (G) with it, facing in use towards said upper die half (3), and an inner bending blade (16) arranged to slide along said outer bending blade (13); said outer bending blade (13) and said inner bending blade (16) having two respective toothed surfaces (13 a) and (16 a) interlocked together and arranged to slide against each other; said cutting blade (10), said outer bending blade (13) and said inner bending blade (16) being movable vertically in a mutually independent manner.
 2. The forming machine according to claim 1, characterised in that said cutting blade (10) is attached to a handling plate (11) which, in turn, is attached to said upper die holder; said upper die holder comprising a plurality of damper pistons (12) arranged to act in use on the upper die half (3).
 3. The forming machine according to claim 1, characterised in that said cutting blade (10) is arranged around said upper die half (3) and said bending blades (13, 16) are arranged around said lower die half (5).
 4. The forming machine according to claim 1, characterised in that said inner bending blade (16) has an oblique upper surface.
 5. The forming machine according to claim 1, characterised in that said cutting blade (10), said outer bending blade (13) and said inner bending blade (16) are connected to respective mutually independent handling means (11, 6, 14, 15, 17, 18). 